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Ransom_RAPID.THEAEAH

August 30, 2018
 Analysis by: Carl Maverick Pascual
 ALIASES:

a variant of Win32/Filecoder.Rapid.A (ESET-Nod32) ; W32/Filecoder.NOZ!tr.ransom (Fortinet)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

915,968 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

15 May 2018

Arrival Details

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Ransomware drops the following copies of itself into the affected system:

  • %Application Data%\info.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It adds the following processes:

  • cmd.exe /c vssadmin.exe Delete Shadows /All /Quiet
  • cmd.exe /c bcedit.exe /set {default} recoveryenabled No
  • cmd.exe /c bcedit.exe /set {default} bootstatuspolicy ignoreallfailures
  • cmd.exe /c wbadmin DELETE SYSTEMSTATEBACKUP
  • cmd.exe /c wmic SHADOWCOPY DELETE

Autostart Technique

This Ransomware modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Encrypter_074 = "%Application Data%\info.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
userinfo = "%Application Data%\recovery.txt"

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software
EncryptKeys =

It adds the following registry entries:

HKEY_CURRENT_USER\Software\EncryptKeys
local_enc_private_key_len = "{Hex data}"

HKEY_CURRENT_USER\Software\EncryptKeys
local_enc_private_key = "{Hex data}"

HKEY_CURRENT_USER\Software\EncryptKeys
local_public_key_len = "{Hex data}"

HKEY_CURRENT_USER\Software\EncryptKeys
local_public_key = "{Hex data}"

Other Details

This Ransomware adds the following scheduled tasks:

  • Encrypter
    • Triggered at initial execution, repeat every 00:01:00 indefinitely
    • Executes "%Application Data%\info.exe"
  • EncrypterSt
    • Triggered at every log on of any user
    • Executes %Application Data%\info.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .rapid

It drops the following file(s) as ransom note:

  • %Application Data%recovery.txt
  • {Encrypted Directories}\How Recovery Files.txt

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.252.04

FIRST VSAPI PATTERN DATE:

15 May 2018

VSAPI OPR PATTERN File:

14.253.00

VSAPI OPR PATTERN Date:

16 May 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Identify and terminate files detected as Ransom_RAPID.THEAEAH

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Task Name: Encrypter - %Application Data%\info.exe
  • Task Name: EncrypterSt - %Application Data%\info.exe

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 5

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\Software
    • EncryptKeys

Step 6

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Encrypter_074 = "%Application Data%\info.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • userinfo = "%Application Data%\recovery.txt"

Step 7

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Application Data%recovery.txt
  • {Encrypted Directories}\How Recovery Files.txt

Step 8

Restore encrypted files from backup.

Step 9

Scan your computer with your Trend Micro product to delete files detected as Ransom_RAPID.THEAEAH. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:

NOTES:

Clean Solution:

To enable Volume Shadow Service,

  1. Run the command prompt (cmd.exe) as administrator.
  2. Enable Volume Shadow Service by typing the following command:

    net start vss

To enable Windows Error Recovery Screen on Startup,

  1. Run the command prompt (cmd.exe) as administrator.
  2. Enable Windows Error Recovery Screen on Startup and use the following command:

    bcdedit /set {default} bootstatuspolicy displayallfailures

To enable Startup Repair,

  1. Run the command prompt (cmd.exe) as administrator.


  2. Enable Startup Repair use the following command: /bcedit /set {default} recoveryenabled Yes


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